STRTOUL(3C) Standard C Library Functions STRTOUL(3C)

## NAME

strtoul, strtoull - convert string to unsigned long

## SYNOPSIS

#include <stdlib.h>

**unsigned long strtoul**(**const char *restrict **__str__,

**char **restrict **__endptr__, **int **__base__);

**unsigned long long strtoull**(**const char *restrict **__str__,

**char **restrict **__endptr__, **int **__base__);

## DESCRIPTION

The**strtoul() **function converts the initial portion of the string pointed

to by__str__ to a type **unsigned long int **representation. First it decomposes

the input string into three parts: an initial, possibly empty, sequence

of white-space characters (as specified by isspace(3C)); a subject

sequence interpreted as an integer represented in some radix determined

by the value of__base__; and a final string of one or more unrecognised

characters, including the terminating null byte of the input string. Then

it attempts to convert the subject sequence to an unsigned integer, and

returns the result.

If the value of__base__ is 0, the expected form of the subject sequence is

that of a decimal constant, octal constant or hexadecimal constant, any

of which may be preceded by a + or - sign. A decimal constant begins with

a non-zero digit, and consists of a sequence of decimal digits. An octal

constant consists of the prefix 0 optionally followed by a sequence of

the digits 0 to 7 only. A hexadecimal constant consists of the prefix 0x

or 0X followed by a sequence of the decimal digits and letters a (or A)

to f (or F) with values 10 to 15 respectively.

If the value of__base__ is between 2 and 36, the expected form of the

subject sequence is a sequence of letters and digits representing an

integer with the radix specified by__base__, optionally preceded by a + or -

sign. The letters from a (or A) to z (or Z) inclusive are ascribed the

values 10 to 35; only letters whose ascribed values are less than that of

__base__ are permitted. If the value of __base__ is 16, the characters 0x or 0X

may optionally precede the sequence of letters and digits, following the

sign if present.

The subject sequence is defined as the longest initial subsequence of the

input string, starting with the first non-white-space character, that is

of the expected form. The subject sequence contains no characters if the

input string is empty or consists entirely of white-space characters, or

if the first non-white-space character is other than a sign or a

permissible letter or digit.

If the subject sequence has the expected form and the value of__base__ is 0,

the sequence of characters starting with the first digit is interpreted

as an integer constant. If the subject sequence has the expected form and

the value of__base__ is between 2 and 36, it is used as the base for

conversion, ascribing to each letter its value as given above. If the

subject sequence begins with a minus sign, the value resulting from the

conversion is negated. A pointer to the final string is stored in the

object pointed to by__endptr__, provided that __endptr__ is not a null pointer.

In other than the POSIX locale, additional implementation-dependent

subject sequence forms may be accepted.

If the subject sequence is empty or does not have the expected form, no

conversion is performed; the value of__str__ is stored in the object pointed

to by__endptr__, provided that __endptr__ is not a null pointer.

The**strtoull() **function is identical to **strtoul() **except that it returns

the value represented by__str__ as an **unsigned long long**.

## RETURN VALUES

Upon successful completion**strtoul() **returns the converted value, if any.

If no conversion could be performed,**0 **is returned and **errno **may be set

to**EINVAL**. If the correct value is outside the range of representable

values,**ULONG_MAX **is returned and **errno **is set to **ERANGE**.

## ERRORS

The**strtoul() **function will fail if:

**EINVAL**

The value of__base__ is not supported.

**ERANGE**

The value to be returned is not representable.

The**strtoul() **function may fail if:

**EINVAL**

No conversion could be performed.

## USAGE

Because 0 and**ULONG_MAX **are returned on error and are also valid returns

on success, an application wishing to check for error situations should

set**errno **to 0, then call **strtoul()**, then check **errno **and if it is non-

zero, assume an error has occurred.

Unlike strtod(3C) and strtol(3C),**strtoul() **must always return a non-

negative number; so, using the return value of**strtoul() **for out-of-range

numbers with**strtoul() **could cause more severe problems than just loss of

precision if those numbers can ever be negative.

## ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

+--------------------+-----------------+

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

+--------------------+-----------------+

|Interface Stability | Standard |

+--------------------+-----------------+

|MT-Level | MT-Safe |

+--------------------+-----------------+

## SEE ALSO

isalpha(3C), isspace(3C), scanf(3C), strtod(3C), strtol(3C),

attributes(7), standards(7)

November 1, 2003 STRTOUL(3C)

strtoul, strtoull - convert string to unsigned long

#include <stdlib.h>

The

to by

the input string into three parts: an initial, possibly empty, sequence

of white-space characters (as specified by isspace(3C)); a subject

sequence interpreted as an integer represented in some radix determined

by the value of

characters, including the terminating null byte of the input string. Then

it attempts to convert the subject sequence to an unsigned integer, and

returns the result.

If the value of

that of a decimal constant, octal constant or hexadecimal constant, any

of which may be preceded by a + or - sign. A decimal constant begins with

a non-zero digit, and consists of a sequence of decimal digits. An octal

constant consists of the prefix 0 optionally followed by a sequence of

the digits 0 to 7 only. A hexadecimal constant consists of the prefix 0x

or 0X followed by a sequence of the decimal digits and letters a (or A)

to f (or F) with values 10 to 15 respectively.

If the value of

subject sequence is a sequence of letters and digits representing an

integer with the radix specified by

sign. The letters from a (or A) to z (or Z) inclusive are ascribed the

values 10 to 35; only letters whose ascribed values are less than that of

may optionally precede the sequence of letters and digits, following the

sign if present.

The subject sequence is defined as the longest initial subsequence of the

input string, starting with the first non-white-space character, that is

of the expected form. The subject sequence contains no characters if the

input string is empty or consists entirely of white-space characters, or

if the first non-white-space character is other than a sign or a

permissible letter or digit.

If the subject sequence has the expected form and the value of

the sequence of characters starting with the first digit is interpreted

as an integer constant. If the subject sequence has the expected form and

the value of

conversion, ascribing to each letter its value as given above. If the

subject sequence begins with a minus sign, the value resulting from the

conversion is negated. A pointer to the final string is stored in the

object pointed to by

In other than the POSIX locale, additional implementation-dependent

subject sequence forms may be accepted.

If the subject sequence is empty or does not have the expected form, no

conversion is performed; the value of

to by

The

the value represented by

Upon successful completion

If no conversion could be performed,

to

values,

The

The value of

The value to be returned is not representable.

The

No conversion could be performed.

Because 0 and

on success, an application wishing to check for error situations should

set

zero, assume an error has occurred.

Unlike strtod(3C) and strtol(3C),

negative number; so, using the return value of

numbers with

precision if those numbers can ever be negative.

See attributes(7) for descriptions of the following attributes:

+--------------------+-----------------+

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

+--------------------+-----------------+

|Interface Stability | Standard |

+--------------------+-----------------+

|MT-Level | MT-Safe |

+--------------------+-----------------+

isalpha(3C), isspace(3C), scanf(3C), strtod(3C), strtol(3C),

attributes(7), standards(7)

November 1, 2003 STRTOUL(3C)